The present invention relates to the series of copper base alloys containing aluminum, and preferably also silicon, plus one or more grain refining elements. It is common practice to add grain refiners to various solid solution, single phase alloys for the purpose of maintaining a fine grain material during processing from the original cast material to the final wrought product. The grain refiner may be added to improve processing and/or to improve properties. In most cases a grain refiner serves to maintain uniform properties over a compositional range and over a range of processing conditions.
Alloys of the foregoing type are, however, often prone to rapid grain boundary failure under stress over the temperature range of from 450.degree. to 950.degree. C. During casting and subsequent direct chill solidification of these alloys, residual stresses may result which subsequently lead to grain boundary sliding, void formation and grain boundary damage when the alloy is heated for hot rolling, as, for example, in the range 870.degree. to 900.degree. C. The defective grain boundaries and low strength of the grain boundaries often result in cracking during hot rolling. This cracking results in significant material losses when the alloy is subsequently processed into a strip product.
It is, therefore, a principal object of the present invention to provide an improved copper base alloy characterized by good hot rollability and good properties.
It is a further object of the present invention to provide an improved, grain refined copper base alloy containing aluminum which is not prone to rapid grain boundary failure under stress at elevated temperatures.
It is a still further object of the present invention to provide an improved copper base alloy as aforesaid which is particularly suitable for processing into wrought products, such as strip, without significant material losses.
Further objects and advantages of the present invention will appear hereinbelow.